1. Field of the Invention
The present invention relates to a surface mount type electronic component mounted on a printed circuit board or hybrid IC (HIC) and a method of manufacturing the same.
2. Description of the Related Art
Known coil components mounded on circuits in electronic apparatus such as personal computers and portable telephones include wire-wound types provided by wounding a copper wire around a ferrite core, stacked types provided by stacking magnetic sheets made of ferrite having a coil conductor pattern formed thereon one over another, and thin film types provided by alternately forming insulation films and coil conductors constituted by metal thin films using thin film forming techniques. The rapid advance toward electronic components having smaller sizes and higher performance in recent years is accompanied by strong demand for coil components having smaller sizes and higher performance. In the case of thin film type coil components, chip size coil components of 1 mm or less are supplied to the market by reducing the thickness of coil conductors.
Patent Document 1 discloses a common mode choke coil as a thin film type coil component. FIG. 4 is an external perspective view of a common mode choke coil 51 according to the related art disclosed in Patent Document 1. In FIG. 4, for easier understanding, visible regions of outer external electrodes 61, 63, 65, and 67 are indicated by hatching, and internal electrode terminals 71 and 73 and features in the neighborhood of the same, which are covered by the external electrodes 61 an 63 and are not visible in practice, are shown in perspective representation. Hidden lines are represented by broken lines.
As shown in FIG. 4, the common mode choke coil 51 has an overall shape in the form of a rectangular parallelepiped that is provided by forming an insulation layer 57 and a coil layer (not shown) formed with a coil conductor in the order listed on a magnetic substrate 53 using thin film forming techniques and combining the resultant stack with another magnetic substrate 55 with a bonding layer 59 interposed between them. The internal electrode terminals 71, 73, 75, and 77 exposed at side portions of the insulation layer 57 are electrically connected to the external electrodes 61, 63, 65, and 67, respectively. The external electrodes 61, 63, 65, and 67 are formed at the respective side portions where the internal electrode terminals 71, 73, 75 and 77 are exposed such that they extend also on the top and bottom of the magnetic substrates 53 and 55 which are substantially perpendicular to the side portions and substantially parallel to the surface where the insulation layer 57 is formed.
Patent Document 1: JP-A-8-203737
The common mode choke coil 51 is completed through a thin film formation step at which the insulation layer 57 and the coil layer are formed on the magnetic substrate 53 in the form of a wafer using thin film forming techniques such as a photo-process, a substrate bonding step at which the magnetic substrate 55 is bonded using the bonding layer 59 formed on the insulation layer 57, a cutting step at which the wafer is cut and separated into chips, and an external electrode forming step at which the external electrodes 61, 63, 65, and 67 are formed. Since a plurality of manufacturing steps are required to manufacture the common mode choke coil 51 as thus described, a problem arises in that the common mode choke coil 51 becomes expensive because of high manufacturing costs. The external electrodes 61, 63, 65, and 67 are formed using, for example, a masked sputtering process. However, it is difficult to form external electrodes 61, 63, 65, and 67 having the shape shown in FIG. 4 on a common mode choke coil 51 smaller than a 1005 type component (the length of which is 1.0 mm along longer sides thereof and 0.5 mm along shorter sides thereof) because of limitations on mask registration accuracy and etc.
It is an object of the invention to provide an electronic component which can be formed with a small size and a low height at a low cost and a method of manufacturing the same.